[pca] Install in Single User Mode?

[Martin Paul]

Romeo Theriault wrote:
> First, Sun "strongly" recommends that the patch clusters be installed in 
> single-user mode. Is it recommended to install the patches with pca in 
> single-user mode? At least the ones that require a reboot to finish? Or 
> is it safe to install them in multi-user mode but with just all the 
> applications using the system turned off?

The recommendation/requirement to install in single user mode is a 
per-patch property; the README of each patch will tell you whether it is 
to be installed in single user mode or not. Quite often, patches which 
require a reboot also are recommended to be installed in single user 
mode, and vice versa.

How hard this recommendation/requirement is debatable. On one hand it's 
Sun which says so, and they should know. On the other hand, people 
(including me) have been installing all patches in multi-user mode for 
years without problems.

If the downtime is no problem it's easy - install everything in single 
user mode. If downtime is a problem, and you can't use Live Upgrade for 
patch installation, and you have good backups, you can install all 
patches on the possibly quietened system. A two stage approach might be 
to install all patches which do not require a reboot (pca's --noreboot 
option) in multi-user mode, reboot to single-user and install the rest.

> Is using pca to install all of the recommended and security patches (pca 
> -i missingrs) equivalent to installing a patch cluster?

Not equivalent, only similar. Sun marks patches as Recommended (R) or 
Security (S) in the patchdiag.xref file used by Sun. pca's missingrs 
will install all patches that are either R or S. The Recommended patch 
cluster contains many of the R/S patches, but not all. In most cases, 
missingrs will install more patches than the cluster. Personally, I have 
two problems with the cluster: You download a lot of patches you don't 
need, and I've seen security patches missing from the cluster in the 
past which is a no-go for me.

> Is installing the patches with pca any faster than installing the 
> patches with the patch cluster? The last patch cluster I installed took 
> about 3 hours. ouch!

Both the install script in the cluster and pca use Sun's patchadd 
command to install patches, so the installation time will be the same. 
pca might be slightly faster as it won't try to install patches which 
are already installed or don't apply to a system. The cluster install 
script loses some time with that, but probably not much.

The real problem here is that patchadd is slooooooow. This has been an 
often discussed issue in the past, but Sun didn't do anything about it. 
With the advent of a new packaging system "soon", don't expect anything 
to happen in that regard for existing Solaris versions.

Hope that helps,

Martin.